The invention relates to a position adjustment device having particular applicability to surgical instrumentation.
In the event of traumas, simple or multiple fractures of one or more vertebrae in the spine can give rise to various configurations that require corrective movements to be applied in order to return the spine to its original shape, in particular concerning the curvature involved in lordosis and kyphosis. Special instruments are used for this purpose that make such restoration possible in cooperation with osteosynthesis systems that are known from elsewhere. Document DE G-91-12 466.2 describes such instrumentation including an adjustment system which comprises a threaded rod having two oppositely-handed threads situated on either side of drive means. Each of the threads engages in a tapped bore of a body connected to an element of the instrumentation. Operating such a system is lengthy because of the pitch of the threads and also because of the fact that during handling, surgical gloves come into contact with the threads which have sharp edges that are liable to catch and tear the gloves, thus requiring additional precautions to be taken. This lengthens the time required to perform an operation which increases the likelihood of harm to the patient.